The invention relates to a suspension for a rigid axle body which is pivotally supported and spring suspended with respect to the chassis or frame of an agricultural or industrial vehicle.
Agricultural and industrial vehicles, such as agricultural tractors, are frequently equipped with a rigid front axle body, which carries steerable wheels. To avoid loss of ground contact by the wheels when encountering uneven ground, the front axle body is supported in pivot bearings on the vehicle chassis. Depending on the vehicle design, which may be in unit body construction or contain a base frame that carries the vehicle components, the front axle body may be pivoted through one or more pivot pins aligned with each other from the front axle support, which is fastened to a vehicle component, or it may be pivoted from a part of the vehicle base frame. The pivot angle is limited so that the axle body and the wheels do not collide with other vehicle components during pivoting. At an excessive pivot angle, for example, the tires as well as the fenders could damage the chassis. The maximum allowable pivot angle depends upon the vehicle geometry and may, for example, amount to 11 degrees. It is therefore desirable to limit the pivot angle of the axle body.
It is also known to support the front axle by springs from the vehicle chassis, in order to improve the safety of operation and the driving comfort of a vehicle, especially at higher transport speeds. For example, EP-B-0 518 226 shows a front axle which is supported from the vehicle frame by a hydro-pneumatic spring arrangement with two hydraulic cylinders. Each of the hydraulic cylinders has one end coupled to a part of the front axle near the front wheels, and another end coupled to a frame component projecting to one side of the engine enclosure. Such an arrangement with hydraulic cylinders cantilevered far outboard limits visibility. If the hydraulic cylinders are relocated further inboard, the axle pivoting angle is limited.